1. Field of the Invention
The present invention relates to a cutting apparatus and method for molding, and more specifically, to a gate cut apparatus and method for a disc molding apparatus.
2. Description of the Related Art
Conventionally, in an injection molding machine, resin heated and melted within a heating cylinder is charged into a cavity formed in a mold apparatus. After the molten resin is cooled and solidified within the cavity, a molded product is removed from the cavity.
For injection of resin, a screw is disposed within the heating cylinder. When the screw is advanced, the resin is injected from an injection nozzle disposed at the front end of the heating cylinder. The injected resin then enters the cavity via a sprue and a gate.
A disc molding apparatus for molding a disc is provided with a gate cut apparatus. After resin is charged into a cavity, the gate cut apparatus is operated in order to separate a molded substrate within the cavity from the gate and to form a hole at the center of the molded substrate.
More specifically, before the resin within the cavity solidifies, the gate cut apparatus is operated in order to extend a cut punch. Subsequently, the mold is opened while the extension force of the cut punch is maintained, and a disc is then removed.
However, in the conventional gate cut apparatus for a disc molding apparatus, since the extension force is maintained even when starting the opening of a mold, the opening of a mold cannot be performed with accurate timing and speed. Therefore, molding defects due to an improper mold release are sometimes produced.
An improved cutting apparatus for a molding apparatus is provided, comprising: a cutting apparatus for a molding apparatus, comprising: a first mold; a second mold disposed so as to face said first mold and to be advanceable and retractable, said second mold forming a cavity in cooperation with said first mold when the movable mold is abutted against the stationary mold during mold clamping; a cut punch reciprocatively disposed to advance into and retract from the cavity; a drive section adapted to advance and retract said cut punch when driven; and a controller controlling the driving of said drive section such that during the mold clamping, said cut punch is advanced at a predetermined extension force in order to perform a cutting of a portion of a molded product within the cavity and such that the extension force is made no greater than a preset value before the mold is opened.